Variable pitch propeller



June 28, 1949. H. J. NlcHoLs 2,474,635

VARIABLE FITCH PROPELLER Filed Aug. 18, 1943 3 Sheets-Sheet 1 p-g- AJune 28, 1949.

H- J. NICHOLS VARIABLE FITCH PB OPELLER Sheets-Sheet 2 Filed Aug. 18,1945 June 28, 1949. H.`J. NICHOLS v VARIABLE PITCH PROPELLER i ssheets-sheet s Filed Aug. 1a, 1945 Patented June 28, 1949 UNITED STATESPATENT OFFICE 8 Claims.

This invention relates to Variable pitch hydraulic propellers,especially for marine vessels and hydraulic turbines, and it has for itsprincipal object the provision of a propeller of the character describedin which the pitch of the blades may be varied accurately while thepropeller is in rotation under load and in Which the blades will beautomatically locked against rotary displacement at all times.

A principal object is to provide an exceptionally simple, strong, andeasily accessible blade actuating mechanism housed in the propeller hub,and a remotely situated primary actuating mechanism housed in a specialflange coupling near the prime mover where it is easily motivated andcontrolled and is readily accessible for lubrication, inspection, andother purposes.

Janother object is to replace the torsion or quill shaft heretofore usedfor varying the pitch of propeller blades by a relatively rigid pushpull rod which greatly increases the rigidity of the -pitch varyingsystem and which avoids any possibility of vibration or flutter of theblades under load due to excessive elasticity of the system..

Another object is to provide a novel and compact shaft coupling unit forvariable pitch propellers having housed therein torque multiplyingmechanism of exceptional compactness relative to its power, therebytoavoid the necessity of inserting special shaft sections and multipleilange couplings in the propeller shafting to accommodate suchmechanism, as in the prior art.

A further object is to provide a construction in which the gears of theprimary actuating mechanism are normally relieved of any strain due tothe blade reaction, thus reducing wear on the gear teeth and enabling arelatively light gear mechanism to be employed.

A further object is to provide a pitch varying system of adequateangular range, including reversing of the blades, which is capable ofchanging the pitch in micrometric increments, yet also is capable ofchanging the pitch at a rapid rate for maneuvering and emergencypurposes. i

With these and other objects in View, as well as other advantagesincident to the improved construction, the invention consists in thevarious parts and combinations thereof set forth and claimed, with theunderstanding that the several necessary elements constituting the samemay fbe varied in proportions and arrangement without departing from thenature and scope of the invention as defined in the appended claims,`

(Cl. Uli-160.35)

To enable others skilled in the art to comprehend the several underlyingfeatures of this invention, that they may embody the same by suitablemodifications in structure and relation to meet the various practicalapplications contemplated by the invention, drawings showing a preferredembodiment of the invention form part of this disclosure, and in suchdrawings like char-` acters of reference denote corresponding parts inthe several views in which,

Fig. 1 is a side elevation in partial axial section of a marine variablepitch propeller and drive shaft therefor embodying certain features fthe invention.

Fig. 2 is a transverse sectional View taken substantially on lines 2 2of Fig. l.

Fig. 3 is a side elevation in partial axial section of the gearmechanism and flange coupling forming part of the invention.

Figs. 4, 5, and 6 are transverse sectional views taken substantially onlines 44, 5 5, and l--S respectively of Fig. 3.

Considering the invention as a whole, and referring particularly toFigs. 1 and 3, a variable pitch marine propeller system embodying the invention is shown as comprising a hollow main drive shaft 9 having acollar or annular flange 49 upset or otherwise provided thereon at itsdriving end, and driving a, tubular propeller sha1-'t I0, having ademountable flange 60, by means of a novel coupling unit 5t whichcomprises a special flange coupling in which is housed a gear-drivenscrew jack. A propeller hub d0 having rotatable blades M is mounted onthe outboard end of propeller shaft l0, the latter housing connectingrod 3i] which operatively connects the screw jack mechanism with theblade actuating mechanism within propeller hub y4l).

The coupling unit 50, the actuating -mechanism of which is preferablydriven by a reversible motor and a transmission chain (not shown), ispreferably mounted inside the vessel at an accessible location. Theentire pitch changing mechanism rotates Ibodily with the shafts at shaftspeed, the gears and other parts of the mechanism being normally at restrelative to each other. the blade pitch is to be changed, the reversiblemotor drives the sprocketv gear l0 of the coupling unit 50 in onedirection or the other relative to` the shafts, thereby producing achange of pitch as described hereafter in detail. Small electricaltransmitters TI and T2, which are driven by the coupling unit, provideremote indication of the pitch angle in connection with otheraccessories not shown.

When

Referring now to the drawings in detail, and particularly to Fig. 1, thepropeller of the invention is shown as comprising a sectional hub 40consisting of a forward portion II which is fixed to the tubular mainpropeller shaft Ill by keys I2, an intermediate portion I3, and an afterportion I4, the latter portions being secured to the forward portion Iiby longitudinally extending bolts I`5; and a hollow cap portion I6 ofstreamline formr which is secured to the, after portion I4 by screws'Il. This hub structure is- Ina-intained against axial displacement bymeans of a split collar I8, engageable with a circumferential groove I9formed in the propeller Shifjfz t0 and clamped between the forward andintermediate portions II and I3 of the hub.

The central portions of thehub are prQvidedy with a plurality ofradially extending bores formed with inner and cuter seats fori rollerbearing units 2| and 22,` respectively, and an annular intermediateshoulder 23.v The, propeller includes a plurality of blades 41;, eachhaving a root` portion journalled in the, bearings 2,/.I and Il, and.,formed with a reduced. threaded, end. 2t on, whichy is screwed a nut 2]which latter alsoA forms the inner race of bearing 2g. 'llhe mit ZTI is.secured against loosening after assembly by. dowel pin 28. A packingwasher 2 4, ot any pre. ferred type is assembled between the blade tl,

and the seat in the hub to prevent leakage of" lubricant and entrance ofwater into the hubA The b lades 4I may be rotated in the hub to.

vary` their pitch from they full forward. pitch to a negative pitch(reverse position) even, while the. propeller is being rotated underload, by means of a connecting rod- 30, which extends4 co-... axiallythrough the drive shaft Illfand is slidable therein, under the action ofgear actuated screw jack means Fig. 3 carried by the shafts for ree.ciprocatng rod 3.0,. Thisrod is providedk with. a q-ross head SI1(triangular in shape for a; three-t bladed propeller as shown in Fig.2f). splined on: red 3Q, and, securedl againstaxial displacement bysplit collar 3-2 seated in a groove on. rod;l 3l), and by; nuts 33 and 34. The after end of. rod; 3m is, jonrrialled,Y in disc` 3,5L which issecuredstmthe hub by` bolts;36. AA gland nut 31A serves as abea-ring forrod 3Q, in shaft I0, and,` alsof. seals the. pro. pelllf' shaft againstentranceof Water.-

Re-ferr-ing to Figs. l and. 2, the. crossrlieada 31|; has. channels 3B.formed inthe edges.. thereof,l and in these channels work slipperblocks. 43. whichA are slidable therein. Openings. 3Q: cut in.

thefprward. walls of channels 38 at the. inner` endpermit assembly of.the slipper blocks in the channels at a nonoperative point. Eachslipperblcck 43,1 hasV a central bore adapted tov receive. a crank pin42 securely mounted onbearinginut 2l: whichis'i'lxed on the root ofifablade;

The cavity of hub `4Il1is providedwith a. supply.v

of;` lubricant which provides; lubrication. for.y thev Working parts ofthe propeller mechanisml Upon reciprocation of` connecting. rod 39:, theslipper blocks 43. are traversed., backy and fonth and. slightlysidewise and, inV so doing. rotate` blades 4I, by meansof crank pins-42; varying. thev Hitch 0f the blades in unison.

The Construction describedy provides.x a strong, durable, positive,and.: efficient` blade twisting mechanismv well: adapted: toJ the.rigid: requirements. off.l marine use.

Referring now toFig. 3 which s'howsthe.d'e. tailsof-r the mechanism forreciprocating thecont. nectin-g rody 3,0,- this mechanism.comprises-a.unit` tary assembly housed in a specialzange 'couconnectingthe propeller shaft lll to the main drive shaft 9, as for example thedrive shaft of a prime mover. The main shaft 9 is shown as beingprovided with a conventional upset iiange 49, while the propeller shaftIt is preferably provided with a keyed, demountable ange 60, constructedin the same general manner as the hub coupling, thereby to enable thepropeller shaft I0 to be withdrawn rearwardly through the shaft bearings(not, shown). The demountable flange structure isv xed to the propellershaft II] by keys 6I and is maintained against axial displacement bymeans of a split collar 6,2 engageable with a circumferential grooveformed in propeller shaft I0. Collar G2 is clamped between ange and ringE3, The flanges 49. to4 6.0l are strongly clamped to the couplingmembers and 66 by through bolts i3d in wellr known. manner. The innerend of rod t is provided with strong threads and is mounted so to bekslidabler coaxially in propeller shaft IAE@ and drive shaft 9.

The torque amplifier mechanism, for increas; ing the torque of thedrivingl motor toiproyidea; powerfulv torque forturning nut, 5&3y ofthef jack: Screw mechanism includes planetary gearing of' differentialtype comprising4 a plurality of retired*e planetary pru'nns 5l, 52.carried by and jouru nalled in planetary pinion carrierAl wheel 53:,ands. meshing with stationaryinternal gear 5A. cut in the inner rim ofstationaryI ring;v 6,6T (see1 Fig. 5),., which also forms a member of.the ange coupling, and with driven internal.v gear- 515, the hub; 56` ofthe latter being mounted. as a free nut om the threaded portionofrod1.3,s. The hub` '5.7 or whee153 is journalled on hub 56.; and therim off' wheel 53 is provided with externalr spur` gearteeth 73, (SeeFig. 4'.) The number of` teeth in stationary gear 54 and; driven. gear55` diilerl slightly, say by one tooth, these gears prefere.bly.I beingcut on. the same pitch circleA Wheel 53 is driven for the` purposeofvaryingthe blade pitch by transmission gearing com. prising. aAplurality of stationary` pinions 'l2 ro.-

pling t tatably mounted in recesses in the harige cour-` pling.y betweenportions 65g and: 56: thereof.; and: a fioating ring sprocket4 1n.having internal gear teeth 'lli meshing with pinions 'I2 and.vexterna-lS teeth` 13. The ring sprocket, gear lll is adapted to bedriven. as required tochange the pitch. by

an. independent. reversible prime mover, pref erably a reversibleelectric motor, by any, suita. ble means, as for example 'by atransmission. chain (not: shown),

Referring to Figs. 1 and 6, for the purpose-s.,y of. providing remoteindicationofthe. pitch4 angle by. electrical means, additionalf gearing.is pro` vided as follows.: ring` member 36', whichL forms part of theliange coupling, isprovided with ex-u ternal gearv teethl 8I1- adaptedto'mesh'withspur gearzl. driving electrical"l transmitter TI, whichlatter is. thereby. driven at a. speed proper-tiniatl tothe shaft1speed-'at' allltimea Also,A drivengear 5 5 is. provided withexternalfteeth l 821* which mesh 5 L withapluralityofstationary-pinions-M rotatably mounted in recesses in member65, which in turn: mesh with I the internal teeth l 86 adapted tof meshwith'` spurl gear 81 driving` electricall transmitter"- T2, which isthereby driven ati a speed* propor tional to.. theA speed ofs drivengear V5'51i Thej dif*- ferential angle of1 the shaftI Inra-nd thedrivenv gear-55:'.thusfreiiectsthepitchanglebfftheblades:

The. electrical pitch. indicating system 'not beingN part: of the'presenti invention; referenceis'fmade; to my.- co-lpendingapplicatienseria1=1^fm 41;'656;

`f the blades.

led July 30, 1948, the same being a continuationin-part applicationbased on a now abandoned application Serial No. 433,991, led March 9,1942 for particulars of that system.

The operation of the blade pitch varying mech anism is as follows:`normally, when the drive shafts are in rotation, the mechanism turnsbodily with the shafts without relative motion of the parts, except thatexternal gears 8| and 81 are uniformly driven `as described above. to benoted that the teeth of the pinions 5l and 52 normally lock the teeth ofinternal gears 54 and 55 together, preventing relative rotation of thosegears. In other Words, the gear system is irreversible and self-locking.In order to change the blade angle, the floating ring gear 10 is drivenor braked by its controlling motor (not shown and which normally isdriven idly) to advance or retard the ring gear 'l0 relative to theshaft. `By means of the transmission pinions` 1,2, the carrier wheel 53`is thus caused to rotate relative to the shafts, and the planetarypinions 5|, 52 to roll around in the internal gears 54 and 55. Assuming,for example, that the pinions have made one complete trip revolvingaround in the internal gears, then the gears 5d and 55 will have gainedor lost one tooth pitch relative to each other, according to thedirection of travel of the pinions. Assuming, for example, that gear 54is provided with 100 teeth, and gear 55 with 99 teeth, then the relativegain or loss will be one tooth pitch per planetary revolution of thepinions or approximately 3.6, thus providing a torque amplification ofapproximately 100m, Therefore, nut 5t will turn 3,6Q on the screw of rod30, forcing a slight translation of that rod, and a micrometric changeof the angle The mechanical advantage of the system will depend onseveral factors, including the pitch of the screw and the radius of thecrank pin from the center of the root of the blade, but it isevident/that the mechanism of the invention provides a very powerful andeiiicient means for varying the blade pitch under load. l

Furthermore, due to the high efhciency of the` gear system, a light,high-speed motor can be used to drive sprocket gear 10, hence rapidchanges of blade pitch can be effected by speeding up the motor asdesired.

It is to be noted that with the mechanism of the invention, the thrustof the blade reaction under load is transmitted by rod 39 to nut 56which is closely and strongly held against translation. The mechanicalelements involved are usuallyrigid and close coupled, hence there is no"opportunity for destructive backlash and vibrau tion to arise from theblade reaction. At the same time, the screw and nut arrangement relievesthe gear system of load except during pitch changing operations.Consequently, relatively light gearing can be employed in the planetaryand transmission gears. The pitch varying mechanism of the invention istherefore well adapted to propeller installations of great power, as forexample, warships and hydraulic turbines,

It is also to be particularly noted that the construction of variablepitch propellers provided by the invention is readily adaptable toequipping existing vessels with such propellers without extensivealteration of conventional propulsion arrangements.

I claim:

l. In mechanical operating mechanism for a variable pitch propellermounted on a hollow pro- It is.

fic

peller shaft driven by a drive shaft, combined coupling and pitchvarying means including a ring member and a flange associated with adrive shaft and a second ring member and a flange associated with thepropeller shaft, a plurality of bolts clamping said rings and flangestogether so as to transmitdriving torque from shaft to shaft, andplanetary differential gearing housed within said ring members andflanges including a stationary gear forming part of one of the aforesaidrings, `a rotary wheel carrying a plurality of planetary pinions meshingwith said stationary gear and driven by transmission gearing externalthereto, and a driven gear meshing with said planetary pinions whose hubconstitutes the rotary nut member of a screw jack pair for varying thepitch of said propeller.

2. In a variable pitch propeller actuating device for connecting ahollow drive shaft to a hollow propeller shaft including a mechanicalcoupling comprising flange members mounted on each shaft, ring membersinterposed between said flange members, a plurality of bolts clampingsaid flange members and said ring members to gether so as to transmitdriving torque from the drive shaft to the propeller shaft, andplanetary differential gearing housed within said mechanical couplingcomprising a sprocket ring gear having external and internal teeth, aplurality of f transmission pinions journalled in said ring members andmeshing with the internal teeth of said sprocket gear, a wheel rotatableconcentrically with the shafts carrying a plurality of planetary pinionsjournalled therein and having external teeth meshing with theaforesaidtransmission pinions, `a stationary internal gear mounted concentricallywith the shaft and meshing with the aforesaid planetary pinions, arotatable driven gear having internal teeth meshing with the aforesaidpinions and having a hub provided with a threaded bore, a threaded rodcomprising a journal for said hub reciprocable within the hollows of theshafts, said hub and said rod forming a rotary nut-and-screw pair.

3. In variable pitch propellers in combination, a hollow drive shaft, ahollow propeller shaft having a partially threaded connecting rodextending coaxially therethrough, a mechanical coupling for said shaftsincluding flange members mounted on each shaft, ring separating membersinterposed between said flange members, a plurality of bolts forclamping and coupling said flange members and said separating memberstogether so as to transmit driving torque, and planetary differentialgearing housed within said mechanical coupling comprising a stationarygear with internal teeth, a driven gear with internal teeth and a hubmounted on said threaded connecting rod as a rotary nut, an externallytoothed wheel journalled on the hub of said driven gear and carrying aplurality of planetary compound pinions journalled therein and meshingwith said stationary gear and said driven gear, and transmission gearingfor driving said wheel comprising a sprocket ring gear having externalteeth and internal teeth, and a plurality of stationary pinionsjournalled in said ring separating members and meshing with the internalteeth of the sprocket ring gear and with the external teeth of theplanetary carrier wheel.

4. The combination of claim 3 in which the compound planetary pinionsare equal, and the stationary gear and driven gear are of substantiallyequal pitch diameter but differ slightly in the number of teeth.

5. In a mechanical coupling device for connectingta tubular propellershaft carrying means for 'varying the Iblade pitch to a :drive shaft 'inaxial alignment therewith, in combination, a hollow coupling structurewith means Ifor connecting said shafts in driving relation, pitchactuating mechanism housed in 'said coupling structure, driving meansfor said actuating mechanism, an external .gear mounted vconcentricallyrotatable ron lsaid structure and connected to :be driven by saiddriving means, a `second external Igear mounted concentrically von `said:structure and connected to be driven thereby, .and transmitter meansconnected to be driven differentially by said external gears, thereby to-actuate remote pitch indicator means in correlation with the angularrelations of said gears.

6. In pitch varying mechanism for a variable pitch lmarine propellersystem including ,3, hub having a plurality of axially rotatable bladesmounted on a tubular propeller shaft, the combination of; means forrotating said blades axially in unison while in rotation including aconnecting rod extending coaxially through said vpropeller shaft andoperatively connected to rotate said blades upon .axial translation;Vand mechanism for 'translating said rod axially 'comprising' planetarydiierential gearing including a i'lxed gear and a driven gear mountedcoaxially -of and around said rod, a rotatable driving wheel mountedcoaxially around .said rod and carrying a plurali-ty of planetarypinions meshing in common with said fixed gear and 4said driven gear,power transmission gearing operatively connected to drive said drivingwheel, and a power screw-jack driven by said differential gearing inwhich the connecting rod constitutes the screw member and the drivengear of said diierentlal gearing constitutes the nut member of .saidscrewjack.

'7. In'mechanical pitch actuating means for .a variable pitch marine.propeller including a hub and a plurality of axially rotatable bladesmounted on a hollow propeller shaft, mechanism for rotating said bladesaxially While Said propeller is in rotation under load comprising.reciprocable means mounted in said Vhub for rotating said bladesaxially in unison, a connecting -rod extending coaxially through saidpropel-1er shaft, and operatively connected to said reciprocalble means,mechanism mounted to rotate with said shaft for reciprocating saidconnecting .rod axially including -a power screw-jack in which a portionof said rod constitutes the screw member o'f the screw-jack, planetarydiierential .gear-ing mounted coaxially around said screw member inwhich the driven Ygear of said gearing constitutes the rotary nut memberof the screw-jack, and power transmission gearing connected to -drivesaid differential gearing.

B. .In fa 'mechanical operating device for avariable 'pitch marinepropeller including ahollow `comeling assembly 'tor connecting adriveshaft in driving relation to the propeller shaft, .mechanism carried by:said coupling assembly for varying the blade pitch `while the propelleris in rotation under .load comprising, in combination, :a powerscrew-jack including a rotary .mit mem-ber and a translatable :screwmember mounted coaxially in fsaid coupling assembly, torque transmissiongearing including a rotatable torque transmitting member mounted-concentrically `on said coupling :assembly and adapted to be :driven bypower means 'external to .sa-id coupling assembly, and means :forfgreatl-y amplifying the torque transmitted by said transmission.gearing thereby to rotate ysaid nut .member -comprisifng ialv.planetary differential gear train 'of high reduction ratio mountedcoaxially on and yaround said screw-jack Iand operatively connected todrive said nut member.

REFERENCES CITED The .following references sare of record in 'the filefoi this patent.:

ULNTED STATES PATENTS Number Name .Date

1,432,090 Simpson Oct. 17, 1.922 1,510,086 Englesson Sept. 30, 19241,590,528 Lansing Jr-ine 29., 1:926 1,855,174 Bakewell Apr. 26, 193211,877,048 Popp -Sept. 13, 11932 1,879,659 Coolidge Sept. 27, 1932`1,917,538 Messing July l1, 1933 1,947,653 Moody Feb. v20, .19342,020,366 -MacCallum Nov. 12, 1935 2,124,078 Palmer et al July 19., 19382,182,504 Whilser Oct. 1:1, 1938 2,236,841 Waseige Apr. 1, 1941y2,265,952 Montgomery Dec. 9, 1941 v2,344,029 Day Mar. 14, 1944v2,370,167 fI-Ioover Feb. 27, 1945 FOREIGN PATENTS Number Country Date3,154 Great Britain Feb. 20, 1891 345,374 Italy Dec. 30., 1936 350,257Italy July 8, 1937 824,546 France Nov. 10., 1937 366,414 Italy Dec. 27,1938 848,267 France Oct. 29, 1939 GTI-IER REFERENCES Stand'elllcontrollable Pitch Propellers from American Society of Naval vEngineersJournal, volume 52, `1940.

